The publication says that: most people with mitral valve prolapse have no symptoms and no complications, need no treatment, and can expect to live as long as people without this common heart problem. But that doesn't mean it should be completely dismissed. Instead, it is a good idea to have it evaluated every three to five years and maintain a healthy lifestyle and regular exercise.

The mitral valve acts as a one-way opening between the heart's left atrium and left ventricle. The valve's two doors, called leaflets, open when the left atrium contracts, pushing oxygen-rich blood from the lungs down into the left ventricle. As the left ventricle contracts, the mitral valve snaps shut. This prevents blood from surging backward into the left atrium, and directs it out to the body instead. In some people, the leaflets of the mitral valve don't fit together tightly, and they bulge or billow backward into the left atrium. This bulging is called prolapse.

In about 10 percent of people with mitral valve prolapse, the condition turns troublesome. Some people feel the heart pause or skip beats (palpitations). Others have chest pain, breathlessness, or unexplained fatigue. The most common complication is mitral regurgitation, which occurs when some blood flows backward through the mitral valve. This makes the heart work harder and can cause symptoms such as chest pain and swollen legs. Another complication is infective endocarditis, an infection of the heart lining.

The Harvard Heart Letter notes that for most people, mitral valve prolapse is an abnormality to be aware of but not worried about.

The Harvard Heart Letter is available from Harvard Health Publications, the publishing division of Harvard Medical School, for $29 per year. Subscribe at www.health.harvard.edu/heart or by calling 877-649-9457 (toll-free).